1. Technical Field of the Invention
The present invention relates to a receiving apparatus for storing data received from the network in a buffer and then reading the data in the buffer based on a reference clock, a transmitting apparatus for transmitting the reproduced data to the network, and their flow control methods.
2. Description of the Related Art
The digital audio/video system capable of achieving the high quality-of-audio reproduction by transmitting the digital audio data or digital video data, which is reproduced by the reproducing device such as the DVD (Digital Versatile Disc) player, etc., to the network including the transmission line such as the serial bus (IEEE Std.1394-1955 IEEE Standard for a High Performance Serial Bus) based on the IEEE 1394 standard, etc. and also receiving the audio data by the receiving apparatus such as the amplifier, etc., is being implemented.
In the related art, the receiving apparatus such as the amplifier, etc. reproduces the audio by reproducing the clock information on the transmitting apparatus side by using PLL on the receiving apparatus side.
However, if such receiving apparatus such as the amplifier, etc. according to the related art is applied to the above digital audio/video system, there is such a problem that the degradation of the quality of audio due to the jitter of the PLL is brought about.
In order to overcome the problem that the above degradation of the quality of audio is caused, the method of applying the flow control method according to the related art to the receiving apparatus is considered.
This flow control method according to the related art is the method that controls the transmitting apparatus by storing the data in the buffer on the receiving apparatus side and transmitting the control signal not to cause the overflow or the underflow, e.g., to maintain the reproducing speed on the transmitter side within the speed variation of ±1%.
If such flow control method according to the related art is applied to the receiving apparatus, the reproduction of the high quality audio can be achieved by storing the data received on the receiving apparatus side in the buffer and then reading the data from the buffer by using the clock with the quartz precision to reproduce the audio.
However, in the receiving apparatus to which the above flow control method according to the related art is applied, if FS (sampling frequency) of the transmitted data is changed during the transmission, the clock on the receiving apparatus side must be changed to meet the changed FS. At this time, since the data stored by using the FS before the change still remain in the inside of the buffer, it is impossible to carry out the reproducing process. As a result, the disadvantages such as the interrupt of the reproduction of the audio, etc. are caused.
The present invention has been made in view of the problem and disadvantage mentioned above, and it is an object of the present invention to provide a receiving apparatus and a flow control method therefor and a transmitting apparatus and a flow control method there for capable of reproducing the high quality audio not to cause the disadvantages such as the interrupt of the audio reproduction, etc. when the sampling frequency is changed.